1. Field of the Invention
The present invention relates to a safety system for vehicle occupants, which safety system enables controlled actuation of safety devices which have not been actuated in an accident.
2. Description of Related Art
A safety system of this type is described, for example, in the article by W. Suchowerskyj “Evolution en matiere de detecteurs de choc” (“Evolution in the Area of Shock Detectors”) in 1141 Ingenieurs de l'Automobile (Automotive Engineers) (1982) No. 6, pages 69 through 77, Paris. The safety system includes at least one sensor, especially a sensor sensitive to acceleration, a control unit, as well as restraint devices such as airbags and seat-belt pretensioners. Modern safety systems are provided with airbags able to be triggered in multistages. Only individual stages or all stages are triggered, depending upon the crash situation. For safety reasons, an activation can only take place when circuit elements in connection with the control unit have enabled the corresponding firing circuits. In many safety systems, this enabling only takes place for a comparatively short time interval on the order of a few 10 ms. If, in the case of airbags able to be triggered in multistages, only one stage has deployed and at least one stage is still capable of being activated, this represents a potential danger for rescue crews at the accident site or for maintenance personnel in the garage, since an uncontrolled triggering of this/these stage(s) still able to be activated cannot be ruled out with certainty in a crashed vehicle. However, the completely unexpected triggering of a restraint device, especially an airbag, can lead to injuries for rescue and/or maintenance personnel not prepared for it. Furthermore, in the case of seat-belt pretensioners equipped with a belt-force limiter, the requirement also exists to activate the belt-force limiter only after a certain time has elapsed since triggering the seat-belt pretensioner. To satisfy these requirements, in known systems, a prolongation of the enabling for the firing circuits is input manually. The manual input influences a computer program which is responsible for controlling the firing circuits. In this known system, a decrease in protection from an unwanted triggering of a restraint device due to an unintended input of an enabling interval which is too long cannot be ruled out with absolute certainty. Moreover, since the enabling is extended only once within an enabling sequence, a poorly selected triggering instant may disadvantageously result in subsequent stages not being triggered, although the severity of the crash actually requires it.